I angle mow, a different direction every time, and I determing the angle by the way the wind is blowing to keep the discharge going away from air cleaners and operator, - I mow a lot of ditches, and sometimes you are spraying the discharge up in the air and it is blowing down your neck, but the rest of the yard does not have to be that way.

So - I do make my first pass somewhere in the yard, but it does not matter if it is the middle or not.

yeah, I always do the perimeter first. As far as where to go after that, depends on how I am cutting, and on the actual lawn layout. Angle I would usually start in the middle and go corner to corner. Parallel, I would follow a property line or straight fixed structure. Either way, I always do the perimeter first.